\tracingonline=2
\tracingcommands=2
\tracingmacros=2
\tracingrestores=2

\showthe\parshape

\parshape=-1\relax
\showthe\parshape

\parshape=0\relax
\showthe\parshape

\parshape=1 1.1pt 2.2pt
\showthe\parshape

\parshape=2 1.1pt 2.2pt 3.3pt 4.4pt
\showthe\parshape

\showthe\parshape

\parshape=1\relax
\showthe\parshape

\parshape=2\relax
\showthe\parshape

\end
